Process for producing an esterase

ABSTRACT

AN ESTERASE ENZYME COMPOSITION COMPRISING THE ACETONE-INSOLUBLE MATTER LEFT ON EXTRACTING LIPIDS FROM THE MARINE INVERTEBRATE PLEXAURA HOMOMALLA (ESPER), 1792, USEFUL FOR TRANSFORMING ESTERS OF PROSTAGLANDINS AND PROSTAGLANDIN-LIKE MATERIALS TO THEIR ACID FORMS.

United States Patent ABSTRACT OF THE DISCLOSURE An esterase enzyme composition comprising the acetone-insoluble matter left on extracting lipids from the marine invertebrate Plexaura homo mallw (Esper), 1792, useful for transforming esters of prostaglandins and pros taglandin-like materials to their acid forms.

BACKGROUND OF THE INVENTION This invention relates to an enzymatic process for transforming prostaglandin esters to their acid forms, to a novel esterase enzyme composition used in that process, and to a process for producing said composition.

The prostaglandins are derivatives of prostanoic acid which has the following structure and atom numbering:

Prostaglandins are known in the art. See, for example, Bergstrom et al., Pharmacol. Rev. 20, l (1968), and references cited therein. For example, prostaglandin E (PGE has the following structure:

Other prostaglandins and prostaglandin-like compounds within the scope of this invention are prostaglandin A (PGA prostaglandin E (PGE prostaglandin A (PGAa), 13,14-dihydro-PGE 13,14-dihydro-PGA 15- methyl (or ethyl)-PGE -PGA -PGE -PGA -PGE and -PGA 13,14-dihydro-15-methyl (or ethyl)-PGE 13, 14-dihydro-15-methyl (or ethyl)-PGA their 15,8-epimers, and their racemates. These compounds and their methyl or ethyl esters are known in the art or are available by methods known in the art. See, for example, Bergstrom et al., cited above, Pike et al., J. Org. Chem. 34, 3552 (1969); Schneider et al., J. Am. Chem. Soc. 91, 5372 (1969); Axen et al., Chem. Comm. 1970, 602; Bundy et al., Annals NY. Acad. Sci. 180, 76-90 (1971); US. Pats. 3,069,322 and 3,598,858; British Pats. 1,040,544, 1,097,533, and 1,202,010; and West Germany Olfenlegungsschrift No. P 21 21 980.7.

The prostaglandins are extremely potent in causing various biological responses and accordingly are useful for pharmacological purposes. See, for example, Bergstrom et al., and other references cited above. Other prostaglandin-like compounds produced in their acid forin by this invention are each useful for at least one of the pharmacological purposes indicated for the prostaglandins, and are used for those purposes in the same manner as the prostaglandins.

The prostaglandins are obtained in a particular optically active form from certain mammalian tissues, for example, sheep vesicular glands, swine lung, and human ice seminal plasma, or by reduction or dehydration of a prostaglandin so obtained. See, for example, Bergstrom et al., cited above, and Nugteren et al., Nature 212, 38 (1966). For convenience hereinafter, use of the terms PGE PGA and the like, will mean the optically active form of that prostaglandin or prostaglandin-like material with the same absolute configuration as PGE obtained from mammalian tissues. Included within the scope of this invention are also the corresponding racemic forms, consisting of the optically active compounds of natural configuration and their enantiomorphs. When reference to the racemic form is intended, either the word racemic or the prefix dl Will precede the prostaglandin name, as for example dl-PGE Following the usual conventions, the hydroxy at 0-15 is shown in alpha configuration, as in FIG. II, by broken line attachment. Compounds with epi (R) configuartion for the hydroxy at C-15 are so designated by using IS-beta in the name. Thus, the ISfl-epimer of PGE; is named 15fi-PGE The corresponding l5/3-epimers are likewise within the scope of this invention.

SUMMARY OF THE INVENTION It is a purpose of this invention to provide a means of transforming prostaglandin esters to their acid forms. It is further purpose to provide a novel esterase enzyme composition useful for that purpose. It is still a further purpose to provide a process for preparing said composition.

Utilization of the prostaglandins and prostaglandin-like materials often requires that they be available in free acid form. They can then be transformed into other desired forms for effective administration, for example salts or esters. However, the prostaglandins and prostaglandin-like materials are not always available in their acid form: when synthesized, they sometimes are obtained as methyl or ethyl esters; in some instances the products are stored as methyl or ethyl esters for stability reasons; and in still other instances these esters may be produced because they provide a preferred form for purification, as by silica gel chromatography. The present invention provides a means of transforming such esters to their acid form in high yield without degradation as an improvement over conventional chemical methods.

I have found an esterase enzyme composition suitable for this purpose. This composition is obtained by processing the marine invertebrate, Plexaura homomalla. Plexaura homomalla is a member of the subclass Octocorallia, order Gorgonacea, suborder Holaxonia, family Plexauridae, genus Plexaure. See, for example, Bayer, The Shallow-Water Octocorallia of the West Indian Region, Martinus Nijhoff, The Hague (1961). Colonies of these Plexaura homomalla are abundant on the ocean reefs in the zone from the low-tide line to about 25 fathoms in the tropical and subtropical regions of the Western part of the Atlantic Ocean, from Bermuda to the reefs of Brazil, including the eastern shore reefs of Florida, the Caribbean island and mainland reefs, and the Gulf of Mexico island and mainland reefs. These colonies are bush-like or small tree-like in habit and are readily identified for collection as Plexaura homomalla (Esper), 1792, by those of ordinary skill in this art. Two forms exist, the R form and the S form. The R form is a source of 15,6 (R) prostaglandins such as 15/3PGA See, for example, Weinheimer et al., Tetrahedron Letters, No. 59, 5185 (1969), and H. W. Youngken, Jr. (ed.), Food-Drugs from the Sea. Proc. Marine Technology Society, pp. 311-3l4 (1969). The S Form is a source of S-configuration prostaglandins, such as PGA One method of distinguishing the two forms is described below in Prepartion 1. For the purposes of this invention either form R or form Sis useful.

The esterase enzyme composition is produced by the steps:

(1) extracting colonies or colony pieces of the marine invertebrate Plexaura homomalla (Esper), 1792, forma R or forma S, with liquid acetone for a sufiicient time to remove substantially all soluble lipids, and

(2) recovering the acetone-insoluble matter as said composition.

The colonies of Plexaura lzomomaI/a are used either in their as-harvested form or in broken or chopped pieces. It is immaterial whether they are used fresh from their natural environment, or after freezing and thawing, or even after drying under ambient conditions.

The extraction with acetone may be done batch-wise, as by stirring in a container, or by percolation, or by continuous methods of extraction known in the art. If stirring is used, it is advantageous to first chop the Plexaura homomalla into small pieces, for example less than 3 mm. in greatest dimension. The product is accordingly then a powder consisting of pieces smaller than 3 mm. Contact with acetone is continued until substantially all of the soluble lipids are removed. Normally one hour is sufficient, although a longer time is required for whole colonies and a shorter time is sufiicient for chopped colonies with efiicient extraction. The end-point can be determined simply by examination of the acetone, as by evaporation and by physical measurements on any residue thus obtained. The extraction temperature is kept below 50 C. to avoid denaturation of the enzyme, and is preferably in the range 20 to 30 C. Lower temperatures may be used but the extraction then proceeds more slowly. The extraction is generally done at atmospheric pressure, but it may be carried out at higher or lower pressures provided the acetone is in a liquid state when contacting the Plexaura homomalla.

Other lipophilic liquids may be used, although generally less effectively than acetone: for example, methanol, methanol-chloroform, dichloromethane, or ethanol-ether.

The acetone-insoluble enzyme composition is recovered from the acetone by decantation, filtration, centifugation, or other convenient method for separating solids and liquids. A small amount of adherent actone, for example of the weight of the'composition, may be left on the product but it is preferred that the amount be lowered to less than 1%, for example by drying under ambient conditions or under reduced pressure. The product can then be stored without deterioration, preferably at about 20 C. The enzyme composition is useful for hydrolyzing esters, as disclosed below.

If desired, an active esterase enzyme can be isolated from the above composition by solubilizing it with an aqueous detergent solution, separating the solution from the skeleton and spicule matter of the invertebrate, and reprecipitating the enzyme esterase as a powder with acetone.

An advantage of the enzyme composition of this invention is that the enzyme is immobilized. The composition is readily recovered from the hydrolysis mixture, for example by filtration, and, after suitable washing and drying, is available for reuse numerous times.

In utilizing the above esterase enzyme composition for the purposes of this invention, the prostaglandin ester is contacted with a mixture of the enzyme composition and water. The ester is conveniently added as a solution, for example in ethanol or benzene, to about 50-10() times its weight of water. The enzyme composition is added in an amount about 1-15 times the weight of ester. The mixture is stirred until the ester is hydrolyzed, generally about 18-24 hours at 25 C. Temperatures of about 0- 50 C. may be employed, although about 25 C. is preferred. The progress of hydrolysis is readily followed by analysis, for example by thin-layer chromatography by methods k own in the art. Se for x p am g 4 et al., J. Biol. Chem. 241, 257 (1966). Finally, several volumes of acetone are added and the soluble acid products are recovered by filtration, concentration, and extraction using methods known in the art.

Accordingly, there is provided a process for producing an optically active acid of the formula XC|ClI -ZCI-I;Clh

(III) or a racemic acid of that formula and the mirror image thereof, wherein is either k or a racemic compound of that formula and the mirror image thereof, wherein R is methyl or ethyl, and wherein are as defined above, with water and an esterase enzyme composition produced as described herein, and (2) separating said acid.

Formula III, which is written in generic form for convenience, represents PGE-type compounds when l I r, is

and PGA-type compounds when 0 I I f i Formula III represents PG -type compounds when X is trans-OH=CH-, Y is CH CH and Z is -CH CH PG -type compounds when X is trans-CH=CH, Y is cisCH=CH--, and Z is CH CH PG -type compounds when X is transCI-I =CH, Y is cis-CH=CH and Z is cisCH=CH; and 13,l4-dihydro-PG -type compounds when X, Y, and Z are CH CH G, R X, Y, andZ DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention can be more fully understood by the following preparation and examples.

All temperatures are in degrees centigrade.

Preparation 1 To distinguish Plevaura homomalla (Esper), 1792, forma R from Plexaura hom'omalla (Esper), 1972, forma S, a TLC method is used. A specimen approximately 2 cm. in length is harvested and placed in a small vial, with a small amount of water if necessary to insure it is wet, and kept closed for 6-24 hrs. About one ml. of methanol is then added and the sample is either shaken for 2 hrs. at about 25 C. or is stored for 16-24 hrs. at about C. A sample of the liquid (1020 ,ul.) is spotted on a TLC plate. It is preferred to use a fluorescent-treated silica gel plate, e.g., Uniplate Silica Gel GF (Analtech, Inc., Newark, Del.). As reference standards, spots of PGA; and 15,8-PGA are also applied. The plate is developed in the A-IX system. The A-IX solvent system used in thin layer chromatography (TLC) is made up from ethyl acetate-acetic acid-2,2,4-trimethylpentane-water (90:20:50:100) according to M. Hamberg and B. Samuelsson, J. Biol. Chem. 241, 257 (1966). The spots are finally visualized with vanillin phosphoric acid spray (McAleer, Arch. Biochem. Biophys. 66, 120 (1957)). Comparison of the unknown with the two reference spots is then made and the identity of the coral established (forma S correspoding to PGA forma R to ISB-PGA EXAMPLE 1.-ENZYME COMPOSITION Freshly harvested colony pieces of Plexaum homonalla (Esper), 1792, forma S (10 kg.), are chopped into pieces less than 3 mm. in their longest dimension, and then covered with about three volumes (20 l.) of acetone. The mixture is stirred at about C. for about one hour. The solids are separated by filtration, washed with 1 2 liters of acetone, air dried, and finally stored at about -20 C. as a coarse enzymatic powder.

EXAMPLE 2.--ENZYME COMPOSITION Following the procedure of Example 1, but replacing Plexaura homomalla (Esper), 1792, forma S with Plexaura homomalla (Esper), 1792, forma R, there is obtained an enzymatic composition.

EXAMPLE 3.--ENZYME COMPOSITION Colonies of Plexaura homomalla (Esper), 1792, forma S (10 kg.) are chopped into pieces, each weighing less than about 2 grams. The chopped material, wet with water, is stored in closed containers for about 24 hrs. at 25 C. and then stirred with about three volumes l.) of acetone at about 25 C. for one hour. The solids are separated by filtration, washed with 1-2 liters of acetone, and air dried, to yield an enzymatic composition.

EXAMPLE 4.-ENZYME COMPOSITION Following the procedure of Example 3, but replacing Plexaura homomalla (Esper), 1792, forma S with Plexaura homomalla (Esper), 1792, forma R, there is obtained an enzymatic composition.

EXAMPLE 5.PGE

A suspension of esterase composition from Plexaura homomalla (Example 1, 2.5 g.) in 25 ml. of water is combined with a solution of PGE methyl ester (US. Pat. 3,069,322, 0.5 g.) in about 0.8 ml. of ethanol. The mixture is stirred at about 25 C. for 24 hrs. Then, 50 m1. of acetone is added, the mixture is stirred briefly and filtered, and the filtrate is concentrated under reduced pressure. The aqueous residue is acidified to pH 3.5 with citric acid and extracted with dichloromethane. The com- 6 bined extracts are concentrated under reduced pressure to the title compound; M.P. l17 C.

Following the procedure of Example 5 but replacing PGE methyl ester with each of the following esters PGE ethyl ester PGA methyl ester PGE methyl ester PGA methyl ester 13,14-dihydro-PGE ethyl ester 13,14-dihydro-PGA methyl ester 15-methyl-PGE methyl ester l5-methyl-PGA ethyl ester 15-methy-l-P'GE methyl ester 15-methyl-PGA methyl ester 15-ethy1-PGE ethyl ester 15-methyl-PGA methyl ester 13,14-dihydro-15-ethyl-PGE ethyl ester 13,14-dihydro-lS-methyhPGA methyl ester 15/3-PGE methyl ester lSB-PGA ethyl ester 15B-PGE ethyl ester 15B-PGA methyl ester 13,14-dihydro-15fi-PGE methyl ester 13,14-dihydro-l5B-PGA ethyl ester 15-ethyl-15/3-PGE methyl ester 15-methyl-15fl-PGA methyl ester 15-ethyl-15B-PGE ethyl ester 15-methyl-15fiPGA methyl ester 15-methyl-15B-PGE methyl ester 15-methyl-15fl-PGA ethyl ester 13,14-dihydro-15-methyl-15B-PGE methyl ester, and 13,l4-dil1ydro-15-methyl-l5fl-PGA ethyl ester,

there is obtained the corresponding prostaglandin-type acid, namely PGE PGA

PGE

PGA

13,14-dihydro-PGE 13,14-dihydro-PGA 15-methyl-PGE 15 -methy1-PGA l5-rnethyl-PGE 15 -methyl-PGA 15-ethyl-PGE 15-methyl-PGA 13,l4-dihydro-l5-ethyl-PGE 13,l4-dihydrol5-methyl-PGA 15B-PGE 15,8-PGA 13 ,14-dihydro-15B-PGE 13,14-dihydro-15/3-PGA 15 -methyl- 1 SB-PGE 15-methyl-l SB-PGA 13,l4-dihydro-15-methyl-15,6-PGE and 13,14-dihydro-15-methyl-l5/8-PGA Following the procedure of Example 5, but replacing PGE methyl ester with dl-PGE methyl ester and with the racemic form of each of the above-listed esters, there is obtained the corresponding racemic acid.

Likewise following the procedure of Example 5, but replacing the esterase composition of Example 1 with each of those of Examples 24, inclusive, there is obtained PGE in each case.

What is claimed is:

1. A process for producing an esterase enzyme composition comprising the steps:

(1) extracting colonies or colony pieces of the marine invertebrate Plexaura homomalla (Esper), 1792 forma R or forms. S, with liquid acetone for a sufiicient time to remove substantially all soluble lipids, and

(2) recovering the acetone-insoluble matter as said composition.

2. A process according to claim 1 wherein the marine invertebrate is Plexaura homomalla (Esper), 1792, forma R.

3. A process according to claim 1 wherein the marine invertebrate is Plexaura homomalla (Esper), 1792, forma S.

4. The esterase enzyme composition produced according to the process of claim 1.

References Cited Adler et aL: The Journal of Biological Chemistry, vol. 236, No. 2, pp. 3240-3245, December 1961.

10 ALVIN E. TANENHOLTZ, Primary Examiner US. Cl. X.R. 19530, 66

UNITED STATES PA rrrce CERTIFICATE @F C@ QT? Patent No. 3,761,556 Dated Sept m 5, 1973 Inventofln) Daniels, Edward G,

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 43, "(I)" should read "(ll)", Column 2, line 26, "is further" should read --'is afurther", Column 5, line #5, "actone" should read --acetone----,. Column 5, line 8, "Plevaura" should read --Ple aura--. Column 5, line 9 "1972 should read "1792",

Signed and sealed this 16th day of April 197Mo (SEAL) Atte st:

EDWARD l l .FLETCHER JR I C. MAR SHALL DANN Atteating Officer Commissioner of Patents U5COMM-DC 6037 6-P69 i ".5. GOVERNMENT PRINTING I @901? 058fl-J34 FORM eo-wso (10-59) 

